South Americans are not considered underrepresented in medicine.
Chances best at DO. I suggest these MD schools:
All SUNY schools
NYMC
Albany
Penn State
Drexel
Wayne State
Oakland
TCU
Tulane
MCW
For DO, add:
DMU
KCU
KCOM (Kirksville)
Marian
LECOM
If you are fluent in Spanish, it would be worth looking into the Puerto Rican schools as well.